Diving and climbing target simulator for ground trainers



June 6, 1950 2. TAKATS 2,510,529

DIVING AND CLIMBING TARGET SIMULATOR FOR GROUND TRAINERS Filed Feb. 21, 1945 4 Sheets-Sheet 1 90'75 so 45 so m 0 I5 30 45 so 1590' L n FIG. I 262 /TAF6ET GROUND RANGE F HORIZONTAL REFERENCE L PLANE.

FIG.4

ZO LTAN TA KATS INVENTOR.

1701? NE V5 June 6, 1950 z. TAKATS 2,510,529

DIVING AND CLIMBING TARGET SIMULATOR FOR GROUND TRAINERS Filed Feb. 21, 1945 4 Sheets-Sheet 2 ZOLTAN TAKATS INVENTOR.

BY%W

@MJ/W ATTORNEj/j June 6, 1950 2. TAKATS 2,510,529

DIVING AND CLIMBING TARGET SIMULATOR FOR GROUND TRAINERS Filed Feb. 21, 1945 4 Sheets-Sheet 3 ZOLTAN TAKATS INVENTOR.

By M

6 mg. /@M@ A TTOR. NEYS Z. TAKATS DIVING AND CLIMBING TARGET SIMULATOR FOR GROUND TRAINERS June 6, 1950 Filed Feb. 21, 1945 4 Sheets-Sheet 4 N 0 4 a 8 .m m .wv I 2 FOLLOW-UP ASSEMBLY VERTICA L SPEED FIG. 8

20 LTAN TAKATS INVENTOR.

ATTORN EYS Patented June 6, 1950 DIVING AND CLIMBING TARGET SIMULA- TOR FOR GROUND TRAINERS Zoltan Takats, Vestal, N. Y., assignor to Link Aviation, Inc., a corporation of New York Application February 21, 1945, Serial No. 579,010

This invention relates to a device for use in training personnel in the use of radar equipment, and more particularly, in the training of personnel to fly an airplane by means of radar.

In order that the general nature of this invention may be better understood, reference is made to Fig. 1 which is a schematic view of one kind of radar screen or C scope I1 and range meter 19 to which the pilot of a combat lane may refer when piloting the plane by means of radar.

Fig. 1 shows that the pilots screen and range meter are side by side. The pilots screen is commonly referred to as the C scope and has upon its face a plurality of horizontal as well as a plurality of vertical lines. A scale is associated with each set of lines, and it will be seen that the central vertical line is designated 0, while the lines to either side of this zero line are successively designated by increasing increments of 15 up to 90.

The horizontal lines are likewise designated in increasing increments of 15 beginning with the designation of minus 20 for the lowermost line and continuing up to plus 60.

The range meter is provided with a needle adapted to move over two scales one above the other, the outer scale being graduated in miles from zero to ten and the inner scale being graduated in feet from zero to fifteen thousand. Means are provided whereby the scales are selectively used, depending upon the distance of the target from the radar equipped plane.

One typical use of radar is in a fighter plane which is attempting to intercept a target plane. It is this particular situation which the preferred embodiment of my invention will be described as simulating, although it will be readily apparent that the invention may readily be applied to the simulation of all types of navigation by radar.

In order that the objects of my invention may be more readily understood the geometrical relationships between a fighter plane and a target plane should be borne in mind. Inasmuch as it is assumed that it is the fighter which is equipped with radar, it is the position of the target relative to the fighter which is considered.

Three factors will locate the position of the target relative to the fighter:

1. Target azimuth angle, which is the angle between the fighters longitudinal axis and the projection of the line of sight from the fighter to the target on the plane through the lateral and longitudinal axes of the fighter. Azimuth is measured from the end of the projection of the longitudinal axis corresponding to the nose of 2 Claims. (Cl. 3510.4)

the plane clockwise or counterclockwise through 180, but the specific type of radar indicating equipment being considered only indicates azimuth up to left or right. If azimuth is greater than 90 the target image is not shown upon the scope.

This definition is illustrated in Fig. 2 where the line LL designates the direction of fiight and the fighters longitudinal axis; the line FTa is the line of sight from the fighter to the target;

FTa designates the projection of the line of sight FTa on the plane P through the lateral T--T' and longitudinal L-L axes of the fighter, and the azimuth angle is so labelled.

2. Target elevation angle, which is the angle between the line of sight from the fighter to the target and the plane through the lateral and longitudinal axes of the fighter.

This definition is illustrated in Fig. 3 where P illustrates the plane of the lateral TT' and longitudinal LL axes of the fighter, F- l'a is the line of sight from the fighter to the target and the target elevation angle is so designated.

3. Target slant range, which is the distance along the line of sight from the fighter to the target is illustrated in Fig. 4.

It is these three factors which are given by the C scope and range meter carried by a real fighter plane equipped with radar. In real radar carried by a fighter plane the plane is equipped with means which cause the image on the scope to be positioned according to the azimuth and elevation angle of the target. Also, the radar equipment causes the range meter to register in accordance with the distance of the target from the fighter. The radar indicating means therefore indicate the azimuth, elevation angle and range of the target.

When the radar equipment carried by a plane is set in operation, if atarget plane be within the field of operation of the equipment, an image such as that shown at To. in Fig. 1 appears upon the screen.

. The azimuth of the target as previously defined is conveyed to the pilot of the radar equipped plane by the position of the image on the screen relative to the vertical line marked zero. If the image appeared as shown in Fig. 1 the azimuth of the target would be 15 degrees right. The target elevation angle is indicated to the pilot by the position of the image relative to the scale at the right of the screen, and in the illustrated case is plus 20 degrees. At the same time the range -meter shows the slant range of the target from the fighter-in the illustrated case the slant range being 8 miles. If the radar equipment continues in operation, and the target remains within the field of operation thereof, the position of the target relative to the fighter is continuously given by the scope and range meter. The position of the target relative to the axes of the fighter as shown by the scope and meter changes in response to the following movements of the target:

1. Changes in the latitude of the target.

2. Changes in the longitude of the target.

3. Changes in the altitude of the target.

Furthermore, the position of the target relative to the axes of the fighter as shown by the radar indicating means changes in response to the following movements of the fighter:

4. Changes in the latitude of the fighter.

5. Changes in the longitude of the fighter.

6. Changes in the altitude of the fighter.

7. Changes in the position of the fighter about its vertical axis.

8. Changes in the position of the fighter about its longitudinal axis.

9. Changes in the position of the fighter about its transverse axis.

As far as the first six mentioned factors are concerned it is deemed unnecessary to show in detail how changes in each of these factors affect the position of the target relative to the fighter in terms of the three basic concepts defined above. It is clear that the relative positions of two points in space in terms of azimuth, angular difference in height and distance may change as either point changes its position in any one of the three possible directions of movement, or combinations thereof. Considering the last three mentioned factors, it is clear that a change in the position of the fighter about its vertical axis, i. e., a turning of the fighter, will produce a change in the azimuth of the target. As far as factor 8 is concerned, let us assume that the target is 90 from the nose of the fighter, i. e., directly abeam, and that the fighter changes its position about its 1ongitudinal axis--that is, it banks. It is clear that the target elevation angle will be changed by-an amount equal to the bank. And as far as the last mentioned factor is concerned, in the event the target is directly ahead of the fighter, i. e., its azimuth is zero, a change in the fighters position about its lateral axis-i. e., a diving or a climbing thereof, will produce a change in the target elevation angle by an amount equal to the change about the lateral axis. Banking and pitching of a fighter plane variously afiect target azimuth angle and target elevation angle, as is well understood by those skilled in the art.

Grounded training equipment for simulating the responses of real radar indicating equipment to changes in the above outlined basic factors in actual flight are known to the prior art. Such training equipment is disclosed in the United States Patent 2,396,857 dated Mar. 19, 1946, and issued to Raymond E. Kittredge for Training device. Referring to Fig. 11, such training equipment may include an aviation trainer of the type covered by U. S. Patents 1,825,462 and 2,099,857. These trainers comprise a fuselage 250 universally and rotatably mounted upon a" stationary base 252. The conventional octagon 254 Y is shown. This trainer in apparatus of the type being considered represents the fighter plane. The fuselage may bank, climb anddive, and it may turn indefinitely in either direction. The student in the fuselage, by means of the rudder pedals 256 in the fuselage which actuate t e urning motor 258, may cause the fuselage 250 to turn in either direction. By means of the control column or stick 266 which is also in the fuselage, the student may cause the fuselage to bank, climb and pitch by means of the banking, pitching and climbing bellows (not shown) which are actuated by the movement of the control column. All of these movements of the fuselage in and of themselves form no part of this invention. For a detailed disclosure of how these fuselage movements may be accomplished, reference is made to United States Patents 1,825,462 and 2,099,857.

As disclosed in the United States Patent 2,396,857, in the interior of the fuselage 250 upon the instrument panel 262 is the previously described radar indicating means, viz., the C scope I! and range meter H! are placed.

Upon a' table I54 remote from the trainer fuselage is a recorder 264 which represents the target, and this'recorder may, under the control of an operator, be made to move in any direction and at varying rates across a chart 266 on the table, as disclosed in the above mentioned Patent 2,396,857. Therefore the direction and=speed of horizontal movements of the target are simulated by the'direction and speed of the target recorders movements.

Also mounted upon the same chart and table is a recorder which shows the assumed geographical location of the fighter. This recorder 268 may be of the type described in United States Patent 2,179,663. Its movement over the chart is automatically directionally responsive to changes in the heading of the trainer fuselage 250 and its speed of movement varies according to the assumed horizontal speed of the trainer. The direction and speed of horizontal movements of the fighter are therefore simulated by the direction and speed of this second recorders movements. Thus, the position of the target recorder 264 on the chart 266 at all times represents the assumed latitude and longitude of the target, while the position of the fighter recorder 258 on the chart 266 at all times represents the assumed latitude and longitude of the fighter. The two recorders are interconnected by arm 210.

These two recorders are mechanically coupled and connected to the radar indicating means I! and I9 so that a movement of either one relative to the other, through an intermediate system of electrical and mechanical elements, produces the same changes in the position of the image Ta on the radar scope and in the range meters reading that corresponding real changes in the latitude and longitude of a real target and of a real fighter would produce on the radar scope and meter in the fighter.

Further, means are provided to change the radar indicating means in response to a turning, banking and pitching of the fuselage 250 of the trainer in simulation of the changes which occur in the radar indicating means carried by a real fighter when the fighter makes corresponding movements. It should be noted that the factors of target azimuth and target elevation angle may change in response to the turning, banking, climbing and diving of the plane equipped with radar, and that the radar indieating meansrespond to these movements. This is because radar equipment is designed to indicate the position of the target relative to the longitudinal, lateral and vertical axes of the radar equipped plane. Latitude, longitude and altitude of the radar equipped plane also are determining factors, but as far as the target is concerned, the only determining factors are latitude, longitude, and altitude. In other words the target may be considered to be a point having location only. 7

Lastly, in trainers of the type disclosed in the United States Patent 2,396,857, a manual control whereby the operator or instructor, may introduce into the mechanism the assumed altitude of the target is provided, and means are employed whereby the assumed altitude of the fighter is automatically introduced into the apparatus. The assumed altitudes of the fighter and target are, in the two just-mentioned applications, differentially combined, the differential result being used to determine the length of one side of a mechanical triangle. By providing a mechanical triangle having one side of a length proportional to the'assumed altitude difference and a, second side of a length proportional to the assumed ground range, as illustrated in Fig. 4 the third side is of a length proportional to target slant range and the angle between the second and third sides is the altitude angle which is defined as the angle between a horizontal plane through the fighter and the line of sight to the target. Altitude angle, when modified by the pitching and banking of the fighter, becomes target elevation angle which is shown by the radar indicating means. My invention relates to improved means for introducing into the apparatus the factor of change in the assumed altitude of the target, and to improved means for combining the assumed altitude of the target with the assumed altitude of the fighter. v

In order that the nature of my invention may be better understood reference is made to the accompanying drawings wherein a preferred embodiment of my invention is illustrated. In the drawings, 1 m

Fig. 1 is an illustrative view of one kind of radar screen or C scope and range meter presently used in radar equipped planes,

Figs. 2, 3 and 4 illustrate certain geometrical relations between two planes in autual flight, Fig. 5 is a disclosure of the fighter altitude transmitter which may be combined with my invention,

Fig. 6 is a detailed view of my improved altitude differential unit, 7

Fig. 6A is a detailed view of a portion of the apparatus shown in Fig. 6.

Fig. '7 is a showing of the instructors control and instrument panels,

Fig. 8 shows in detail a portion of theinstructors control panel,

Fig. 9 is a circuit diagram of a part of my invention,

Fig. 10 is a schematic showing of the mechanical triangulating means which may be used with my invention, and

Fig. 11 is a general view showing training equipment of the type to which this invention relates.

The disclosed embodiment of my invention in!- cludes in several places the well known system of remote actuation by Teletorques and Telegons. A general explanation of this system is therefore believed desirable. Each of these systems includes a transmitter and receiver suitably supplied with electrical energy and connected by means of a cable. The transmitter includes a housing and a rotor, the rotor usually being referred to as, the input shaft, and the receiver also includes a housing and a rotor, but the rotor of the receiver is referred to as the output shaft. When the input shaft of the transmitter is turned in one direction, the output shaft of the receiver simultaneously moves in one direction and through the same angle. By selectively coupling the transmitter and receiver, for a movement in one direction of the input shaft the output shaft may bemade to move in the desired direction. Teletorques are used when a relatively strong source of power is available to move the input shaft; otherwise Telegons are employed.

Target altitude angle has been defined as the angle between a horizontal plane through the fighter and the line of sight from the fighter to the target. This concept is illustrated in Fig. 4 where the point P represents the position in space of the fighter plane and the line L-L' represents the direction of movement of the fighter while the point Ta represents the position in space of the target plane.

Target Slant Range is defined as the distance along the line of sight from the fighter to the target and in Fig. 4 is represented b the line so designated. Target Ground Range is the horizontal projection of the target slant range and isillustrated in Fig. 4 by the line designated target ground range.

Altitude differential is defined as the difference in altitude between the fighter and target planes, and is represented in Fig. 4 by the line so designated.

From this discussion of Fig. 4 it will be appreciated that given the factors of ground range and altitude differential, the factors of altitude angle and slant range may be readily determined. Means for introducing the factor of altitude differential into a mechanical triangulating unit will now be disclosed.

Altitude differential is the difference in altitude between the fighter and target planes. When the target is higher than the fighter the altitude differential is considered positive; when lower it is considered negative.

From' this definition of altitude differential, it will be realized that in order to introduce this factor the two basic factors of fighter altitude and target altitude must be combined to give the resulting altitude differential.

First, means will be described for introducing the factor of fighter altitude, then means will be disclosed for introducing the factor of target altitude, and then it will be shown how these two factors are combined in this invention to give the factor of altitude differential.

As is well known the altitude of a plane in actual flight depends upon two basic factorsfirst, the power setting of the plane and second,

the attitude of the plane, i. e., whether the plane is climbing or divingand, of course, the length of time that the plane has flown at its various powersettings and attitudes.

In trainers of the type disclosed in U. S. Patent 2,099,857 there is an altitude tank connected-to a source of reduced air pressure and to the atmosphere. When the combined positions of the simulated throttle lever and attitude of the fuselage'are such that if a real airplane had a corresponding throttle setting and attitude the plane would gain altitude, the tank in the trainer is connected through a valve to the source of reduced pressure. On the other hand, when the combined positions of the simulated throttle lever and'fuselage attitude are such that if a real airplane had a corresponding throttle setting and attitude the plane would lose altitude, the tank at ases 7. in. the trainer is connected through. a valve; tothe atmosphere. In; this way the pressure within the. tank is. always inversely Proportional to the assumed, altitude of the trainerthe higher the pressure the; lower the assumed altitude.

Re erence. is made to Fig. 5,- which is a. detailed disclosure ofv the fighter altitude transmitter which may be combined with my invention. The apparatus shown in Fig. is designated generally; by- 2-19, and: its general location is shown in Fig. 11. In Fig, 5 the altitude tank is. designatedv 2d, the connector 2%, and this, tank is preferably in the Link trainer which, as is fully explained in the United: States Patent 2,396,857, represents the radar equipped fighter plane. The pressure; within thistank, it may be concluded, varies inversely with the assumed altitude of the fighter represented by theLinl: trainer.

In. Fig; 5' thealtitude tanlr, 2. 3. is shown, to be connected by means of line-22 to the large collapsible-enpansible bellows. 24. Afrlxedto the upper end of bellowsv 2 3 is member 26 which has a slot 23 and pin 33 arranged to hold one end of reciprocating arm 32' which travels ina plurality of; rollers suitably attached to plate 36 which isa-flixed to the inside of the" fuselage of the Link trainer or equivalent device. To the other end of, arm 32 is affixed cord 33 which travels in pulley 4E1 suitably held by shaft 42 which is held plate 35. The other end of this string is affixed to one end of tension spring 4d, the other end of which is suitably attached to any fixed part i'ajof the unit.

A. plate 48 is pivoted at the-point 5%! to a suit.- ablefixed part. of the unit, and formed integrally with plate 38- gear segment. 52. A tension spring 5% is suitably: attached to a corner of gear segment 52 as shown, the other end of this spring; being; attached to a part 5% of the unit. A shaft 58 is aflixed'to. slide 32' and shaft 56 has mounted thereupon near its outer end roller 6i], and a spring; 52 has one of its ends attached to the extren e outer end of shaft 58 while; its other end is suitably attached to a, bolt 64 carried by plate 48. A plate 65, made separate from plate it for adjustment purposes, and havingan arcuate slot 68 is suitably attached to the inside of plate 48 by means of a pair of bolt,,nut and slot arrangements It.

Meshing with gear segment 52 is pinion '32 formed integrally with, shaft. M held by bracket 76 attached to plate 36. Fixedly mounted upon this: shaft is is a large spur gear I8. The input shaft 83 of the fighter altitude-transmitting Teletorque 82 is connected to shaft 14 for rotation therewith. TransmitterSZ is connected by means of cable 84 with fighter altitude receiverv Teletorque 85 shown in Fig. 6.

Reference, is made to Fig. 6 which is a detailed view of the altitude integrating unit which forms an important part of; my invention. This unit is designated generally by 8? and may be located as show-n in Fig. 11. Upon the output shaft 88 of fighter, altitude receiver 86 is carried a disc S'll-Which has attached thereto an arm 82 carrying contact roller 95'. The assembly designated generally 96 includes a pair of split contact segments 93 and I639 carried. by an insulating disc 592. As seen in Fig. 6A, a pair of collector rings 99 and 99a are mounted upon the other side of the insulating disc I82 from the contact segments, these collector rings being concentric, mutually insulated and each is engaged by the brushes IM or IE5. Also, the collector ring 59 is. in electrical contact. at all times with the-segment. 98 and, ring 99a is; similarly arranged with respect to the segment [00. Further, the segments 98. and I00 are mutually insulated, Drive motor I08. is connected to the brushes H114 and Hit by means of conductors H0 and. H2 When the. contact roller 94 engages both of the split segments 98 and I00, motor M18 is notenergized. But when as a result of the. rotation. of the output shaft 8530f the fighteraltitude receiver 85 roller 94 is moved outv of, engagement with one of the split contact, segments, 93 or I-Dil, motor I 58 is energized, the direction of turning of the motor dependingupon which segment is out-of contact with the roller, 94. Whenever motor I08 is energized, by means of gear train H4 which includes gears U la, H41) and H40, the shaft I It having formed integrally therewith thev worm I It is rotated and gear I20 fixed-1y mounted upon the input shaft I22 of the; al-titudediiferential I24 is turned. The. turning of shaft I22 at-the same time results in a rotation of gear I25 which is aflixedupon this; shaft and gear I25 drives gear I26 which is fixedly mounted upon the, shaft I28 carrying the split contact. segments, insulating disc, and collector ringsof the assembly 98.. M0.- tor I08 therefore continues to run until it repositions the assembly 96 to the point that both of the split contact segments againare inengagement with the contact roller. 94-. Atthis instant motor I08 stops.

Thus motor IIIB- is directionally controlled by the direction of rotationof the output shaft 88 of receiver 86, and the magnitude of the output of the, motor dependsupon the angle through which shaft 88 is turned. I

Referring again to Fig. 5, a reduction in the pressure within the altitudetanlc 22 which, as previously explained occurs whenever there is an increase in the assumed altitude of the fighter, I2, causes a collapsing of bellows 24 and slide 32' will move downwardly in Fig. 5. A movement in that direction will result in a similar movementof shaft 58 and: roller 6.0. This: roller. coacting with arcuate slot 68 causes a counterclockwise-pivoting of plate 48 resulting; in. a clockwise; turning. of pinion I2, gear 78 and of the input.- shaft of the fighter altitude transmitter 82. The output shaft 88 of the fighter altitude receiver 86, shown in Fig. 6, will therefore move in the desired direction, resulting in an energization of follow-up motor I08 which will turn theoutput shaft i IS in the properdirection. The input shaft $22 of the altitude differential I2 3 will therefore be rotated and at the same time the split gear segments 98 and III!) of assembly 96 are properly rotated to bring both of these segments backinto engagement with contact roller 94, at which instant motor I08 stops.

An increase in pressure within the altitudetank 22, on the other hanchwill result in an. expansion of bellows 24 and by means of the just disclosed apparatus the follow-up motor I68 will be energized in the opposite direction fromthat explained in the preceding paragraph and the direction of movementof the input shaft I22 of differential I24- will be in the opposite direction. Similarly, the splitgear" segments 98 and I08 of assembly 96-will be rotatedin. the opposite direction to bring both of these segments back; into engagement with contact roller 94.

The foregoing discloses therefore means whereby the-input shaft- I22 of the altitude differential I24 is rotated directionally and in magnitude in accordance with changesin, the assumed. altitude of the. fighter representedby the Link trainer.

Parenthetically, it can be here pointed out, that mounted upon the right end-of shaft I22, as seen in Fig. 6, is the primary member I36 of a permanent-magnet type magnetic coupling, the other member of which is I32. These conventional magnetic couplings are used for ease in installation. Member I32 is afiixed upon the input shaft I34 of the fighter altitude transmitting Telegon I36 which is connected by means of cable I38 to a receiver Telegon I39 which is a part of the instructors fighter altimeter I46, seen in Fig. '7. By virtue of this magnetic coupling shown in Fig, 6 the input shaft I34 of the'fighter altitude transmitting Telegon I36 rotates in accordance with the rotations of the input shaft I22 of the altitude differential. The output shaft of the receiver Telegon in simulated altimeter I46 follows the movements of the input shaft I34, as is well understood in the art, and therefore the altimmounted upon the students instrument'panel in the Link trainer. Rotations of gear I42 in' response to changes in the assumed altitude of the fighter thus aifect the indications ofthe simu-' lated altimeter which indicates to the student in the Link trainer his assumed altitude.

- Considering now the factor of'assumedtarget altitude, reference is made to Fig. '7 which is a detailed disclosure of the instructor's control and information panels. In Fig. '1 the table I54 is provided, and it is upon this table that the fighter andtarget recorders are mounted for movement to simulate changes in the assumed latitude and longitude of the fighter and target planes. The instructors control drawer is designated I56 and his information panel is I58.

As seen inFig. '1,.there is disclosed a knob I66 affixed upon the upperend of vertical shaft I62 which positions the contact. (not shown) of potentiometer I64. A pointer I66 is also attached to the vertical shaft. I62 and arranged to move over a dial I68 Whichis afiixed upon the top I69 of the instructors control drawer I56. The ,po-.

tentiometer I64 is connected to motor I16inFig, 6 by means of cable I12a. x

As shown in Fig 8, dial I68 is calibrated to represent the assumed target. vertical speed.

Reference is now made to Fig. Qwhere the field windings and. armature of themotor'iI16' are shown together with the potentiometer I64, a double-pole double-throw reversing switch I12, a conventional timer I14 and a reset switch I16. By reference to Fig. 9 is seems clear without a detailed description that the setting of the potentiometer I64 determines the speed of motor I16 While the setting of the reversing switch I12 determines the direction of running of this motor. Also, when the reset switch I16 is pressed by the operator, the switch I18 in the timer I 14 is closed, thus setting the motor I16 in operation at a rate dependent upon the setting of potentiometer I64 and in a direction dependent upon the position of switch I12.

With this arrangement the instructor may set the knob I66 so that the pointer I66 indicates in conjunction with dial I68 the proper assumed target vertical speed, reversing switch I12 according to whether it is assumed that the target .is climbing or diving, and by means of knob I11 .of the target to take place. These steps having been taken, motor I16 in Fig. 6 runs in a direction,

.at a. speed and for a length of time that the assumed vertical movement of the target occurs. When the assumed time has elapsed, timer I14 opens switch I18 and motor I16 stops.

Referring now to Fig. 6, afiixed upon the output shaft I86 of motor I16 is the worm I82 which drives the worm gear I64 affixed upon shaft I86 which has upon its outer end worm I88 arranged to drive the worm gear I96 affixed upon the second input shaft I92 of the altitude differential I24. Inasmuch as the direction of turning of the output shaft I66 of motor I16 is in accordance with the assumed direction of vertical movement of the target while the speed of motor I16 is proportional to the assumed rate of vertical movement of the target, and inasmuch as this motor runs for as long as the target is assumed to be moving vertically, it is clear that the shaft I92 introduces into the altitude differential I24 a movement proportional to assumed changes in the altitude of the target. The differential I 24 therefore combines the movements of shaft I62 and those of shaft I22the movements of the latter shaft being in accordance, with the assumed changes in the altitude of the fighter represented by the Link trainer-50 that the gear I94 affixed upon the frame of the differential I24 has a total movement imparted thereto proportional to the difference between the assumed altitude of the fighterand the assumed altitude of thetarget.

Thus the gear I94 is always positioned in accordance with the assumed altitude difference. This same motion is transmitted to the gear I96 which is mounted upon the input shaft I68 of the altitude difference transmitter 266 which is connected by means of cable 262 to the altitude difference receiving Teletorque 264 shown in Fig. 10. (Parenthetically, referring to Fig. 6, by means of magnetic coupling 226 arranged to turn the input shaft 222 of the target altitude transmitting Telegon 224 connected by cable 226 to a receiver Telegon associated with target altitude indicator 228 seen in Fig. '1, the indicator 226 at all times indicates to the instructor the assumed target altitude.)

The output shaft of the altitude difference receiving Teletorque is arranged to energize a motor 1 which is apart of the schematically-shown follow- 5 up assembly 266 so that the output of this motor is directionally controlled according to whether there is an increase or decrease in the assumed altitude difference. Further, this motor has an output proportional to the assumed altitude difference. Inasmuch as this follow-up assembly is similar in construction and operation to the follow-up assembly described in detail in connection with Fig. 6, a detailed showing and explanation at this point is deemed unnecessary.

Still referring to Fig. 10, there is shown schematically a mechanical triangle comprising a ground range side 268, an altitude difference side 2H! and a slant range side 2I2. Illustratively speaking, the slant range arm 2I2 may be pivoted to the fixed ground range arm 268 at the fixed point 2I4, and the pivoted slant range arm 2I2 may be slidably pivoted to the altitude difference arm 2 I6 at the point 2 I 6. The altitude difference arm crosses the ground range arm 268 at the movable point 2I8, arm 2I6 being slidable along arm 208 but always being positioned perpendicular thereto. Thus the distance from the fixed point 2M to movable point H8 is variable but always proportional to the assumed ground range, movable as disclosed in the above mentioned Patent 2,396,857. Means may be provided for moving the altitude difference arm 210 to the left of point 2! in accordance with changes in the assumed ground range as determined by the distance between the fighter and target recorders upon the table 154. Also, the distance from the point M8 to the movable point 2l6 is variable but always proportional to the assumed altitude difference, and as shown in the same copending applications, the arm 2l0 may be positioned by the motor in follow-up assembly 206 through the driving connection 209 so that the distance from point 2 l8 to point 216 always is proportional to the output of the altitude differential 124 seen in Fig. 6. Thus the distance from point 214 to point H6 is variable and always proportional to the assumed slant range and the angle between arms 208 and 212 is variable and always equal to the assumed altitude angle. The distance from point M4 to point 215 may be measured by a suitable take-off to cause the range meter l9 to indicate the assumed slant range, While the altitude angle may be introduced into suitable mechanism to be integrated with the pitching and banking attitude of the Link trainer to produc the assumed elevation angle which properly positions the image To on the screen H as far as elevation angle is concerned.

M invention therefore discloses a novel arrangement for differentially combining the assumed fighter and target altitudes to properly position an element in accordance with this assumed factor. Also, a much superior arrangement for introducing the factor of assumed target altitude is provided. The instructor may change the factor of assumed target altitude over any desired length of time, at any desired rate and in either direction. Thus the factor of assumed target altitude is introduced into the mechanism in close simulation of the manner that a real target plane in actual flight would change its altitude. Consequently, the range meter and screen have their indications changed ver realistically.

Those skilled in the art will appreciate that many changes may be made in the preferred disclosed embodiment of my invention without departing from the substance thereof. Also, my invention may be used for other purposes than those specifically disclosed herein. Such changes and uses are intended to be covered by the following claims.

I claim:

1. In a grounded navigation training system the combination of an instrument for indicating the assumed altitude of an airplane; a motor connected to said instrument for changing the indication of said instrument; a circuit associated with said motor and including a switch for starting said motor, a reversing switch for determining the direction of running of said motor and a potentiometer having a movable part for determining the speed of said motor; means for positioning the movable part of said potentiometer according to the assumed vertical speed of an airplane; means for positioning said reversing switch according to the assumed direction of vertical movement of an airplane; and means including a selectively operable timing device for stopping said motor after the elapse of a selected time from the closing of said first switch.

2. In a grounded navigation training system the combination of a dial graduated in terms of assumed vertical speed; a pointer arranged for movement over said dial; a motor; a circuit including a first switch, a potentiometer having a movable part for determining the speed of said motor and a reversing switch for determining the direction of said motor; means movable with said pointer for changing the position of the movable part of said potentiometer; means for positioning said reversing switch; means for closing said first switch; and a timer for opening said first switch after the elapse of a preselected length of time from the closing thereof.

' ZOLTAN TAKATS.

REFERENCES CITED The following references are of record in the file of this patent:

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